C4 - have to rev up before it engages

[bralston]

I have a automatic c4 trans in a 76 bronco. the trans runs and shifts fine, no weird noises or smells. the problem is that I have to initially rev the engine up to get it to shift into gear, forward or reverse. sometimes i really have to rev it up, usually once it warms up 10 minutes of driving its fine. When I rev it, the trans jumps into gear and accelerates fine. Sometimes it will slip out again and I will have to rev it up again to engage. this only happens when I first start driving it.

 

[SteveL]

Check the fluid level. If the level is low it will do this til it's warmed up.

 

[bralston]

questions : I check the fluid with the vehicle running ? Can you overfill ?

 

[Broncobowsher]

You check it with the engine running
You can overfill it.

If I remember the C4 right, there is a low and full mark that should be checked at normal operating temp of the transmission. There is also a "do not drive" mark at the bottom of the stick. With it running and cold (on level ground) it should be between the "do not drive" and the full mark. Warmed up, between the low and full marks.

If you can't find where the transmission fluid is going, with the engine off pull the vacuum line off the back of the transmission modulator (only vacuum hose(s) going to the transmission). If transmission fluid comes out of the hose, the modulator has a pin hole in it. Otherwise it has to be leaking it on the ground.

 

[bralston]

dually noted. I will apply that information accordingly and hope it fixes the problem.

 

[ken75ranger]

Sounds like the seals are going bad.

 

[A4x4Junky]

Sounds like the seals are going bad.

I would agree. Once the seals start to harden up you sometimes will need to build pressure before you will have engagement. My C-6 was the same way.

Anthony

 

[wildbill]

;D ;D ;D I had 1/2 ton ford pu that did that. It was the torque converter was bad. I cheated I drained all the trans oil and filled with 20 motor oil worked realey good drove the truck over 2 more years and put a BIG motor in it. But you need to look at the torque converter good luck. Bill ;D

 

[catfish1512]

You can try the transmission stop leak stuff from the local parts store. What it does is swells the seals to keepem from leakin which may help with the pressue issue.

 

[surfer-b]

Have you changed the filter and fluid, does the fluid look red or does it have a dirty color to it, does it smell burnt?